Share
Explore BrainMass

E.coli

A nutritionally defective E.coli strain grows only on meduim containing thymine, whereas another nutritionally defective strain grows only on meduim containing leucine. When these two strains are grown together , a few progeny are able to grow on minimal meduim with neither leucine nor thymine. How can this result be explained?

Solution Preview

Bacterial Conjugation

=====================

E. coli that can only grow on medium containing thymine are called thymine auxotrophs (thy-).

E. coli that can only grow on medium containing leucine are leucine auxotrophs (leu-).

Obviously, thy- is wild-type in all other genes; therefore, they are really thy-/leu+.
Same logic applies for the leucine auxotrophs. They are really thy+/leu-.

But how can a wild-type bacteria come out of this mixture? ...

$2.19